.

                                      A
                            c       c   t         c
                        t            i   o             t
                      i                n                 i
                     o                A                  o
                     n                c                   n
                    A                 t                   A    
                     c             i       o              c
                      t            n       A            t
                        i            c     t            i
                          o            i             o
                              n       o         n
                                        n